Huston! We have a problem!

25 posts in this topic

Posted

I was mounting the data plate and decided to pull the trim panels off underneath the horizontal stab since I had not looked at the elevator rear connection yet. Here is a series of pictures of what I found. Something does not look right and since I have no reference or built the plane I would like your input.

2017-10-02 20.05.09.jpg

2017-10-02 20.05.29.jpg

2017-10-02 20.06.32.jpg

Share this post


Link to post
Share on other sites

Posted (edited)

I'll start by saying that this bolt and nut are hitting the front tubes and have actually worn a groove in the nut. Yes they used a nyloc nut here.  More pictures....

2017-10-02 20.07.04.jpg

2017-10-02 20.07.39.jpg

Edited by rvsimons

Share this post


Link to post
Share on other sites

Posted

So I spoke with Joey and he said to put a low profile head bolt and castle nut on. I did and as you can see its still hitting on both sides on both tubes. If I used a Phillips head bolt it would fix one side but the side with the nut would still hit the tube. Last pictures.

2017-10-02 20.08.05.jpg

2017-10-02 20.08.28.jpg

Share this post


Link to post
Share on other sites

Posted

Damn, that is a tight spot!  What about a Clevis pin?

 

1 person likes this

Share this post


Link to post
Share on other sites

Posted

I am looking through the manual to see what is recommended. Haven't found an exploded view yet.

Share this post


Link to post
Share on other sites

Posted

Just looking at my manual, and it says there should be 30 degrees of up movement, and 17 degrees of down movement on the elevator.  Maybe if you have more travel than this, that is why the bolt is hitting??  JImChuk

Share this post


Link to post
Share on other sites

Posted

So how much down elevator travel do you have? The manual indicated limit  I am taking from memory is 17 degrees. Where are you at?  

Share this post


Link to post
Share on other sites

Posted

I will check the travel tommorow. Have to be up for work at 4 am. :)

Share this post


Link to post
Share on other sites

Posted (edited)

The horn looks to me like it's been cut (broken) off and made shorter for more elevator travel. 

That is a nasty looking weld on it. 

Edited by Av8r3400
1 person likes this

Share this post


Link to post
Share on other sites

Posted

The horn looks to me like it's been cut (broken) off and made shorter for more elevator travel. 

That is a nasty looking weld on it. 

I would agree. Something has been modified by the looks of it. I was hoping someone might have a picture of what this should look like. It seem stout enough but it looks like hell. Do these planes utilize stops on either end of the throw?

1 person likes this

Share this post


Link to post
Share on other sites

Posted

Here is what I found. The down throw was over 20 degrees. I reset the ends and added a stop. Now I have 17 down and 30 up. The problem with the bolt nut hitting the structure is still an issue. I called a local builder I trust and he said to use a pin with washer under the head and pin and make sure no side to side slop was present. I found a new pin in my hardware and added a thin washer inside the end to take out the slack. A thin washer under the head and pin made a good fit. Here is a picture. 

I'd like to hear what you guys think. I'm kinda out of my realm on the pin verses bolt thing. 

2017-10-03 18.15.29.jpg

Share this post


Link to post
Share on other sites

Posted

Here is how I added a stop. I took an AN 3 large washer and drilled the hole to 1/4". I added another stop nut and added the washer between the stop nuts. The washer now acts as a stop when you let the stick all the way forward. 

2017-10-03 18.19.26.jpg

2017-10-03 18.16.10.jpg

Share this post


Link to post
Share on other sites

Posted (edited)

You had a pin that exact size in your hardware!  Wow man!

I'd fly it like that, but my "imo" aint worth much..  lets hear some sage advice from guys like Jim, Ed, and others.

The washer stop would give me more pause, since it could bend and get jammed in there.  But that is so dang unlikely.

Edited by MN Kitfox 2

Share this post


Link to post
Share on other sites

Posted

I went to an estate auction of a local plane builder and bought a ton of AN hardware. It comes in real handy. :)

Share this post


Link to post
Share on other sites

Posted

Looks good!  I’ve used those Clevis pins like that and have had no problems...it’s not like you could get an side load on them anyway with all of the close tolerances.  Safer than it was for sure!

 

Ron

Share this post


Link to post
Share on other sites

Posted (edited)

The stop you have made with the washer puts pressure on the Heim joint threads.  There was a AD or SB on that from Avid a long time ago.  I made a stop out of some aluminum angel that went from the floor board to the bolt head that the joy stick pivits on.  Some one had the heim joint threads break from the over bending it got because there was no stop and pushing the stick all the way forward would wrap the joint over the control cross tube.  Don't remember if they lost their elevator on the ground of in the air, but everyone should have a stop in place to keep this from happening.  Doug probably can pull up the Avid paper work on their recommended fix for this.  Here is a picture kind of showing what I did.  JImChuk

I meant to go measure the length the horn on the elevator should be today, but didn't get to it, when I thought of it, I said later, and then it slipped my mind.  I'll try again tomorrow.

 

Photo0877.jpg

Edited by 1avidflyer

Share this post


Link to post
Share on other sites

Posted

Thanks Jim. So I did a little research during dinner (wife loves it when I do this) and it says that clevis pins are not to be used for this. It said " Used with clevis forks and in secondary controls which are not subjected to continuous operation." Well I would say the elevator is continously operated. I went back out and searched my hardware again and found a low profile head sheer bolt and a low profile castle nut. I put them in and they are as close as I'm going to get. The clearance is still minimal but at least I have some. I guess I will have to live with that. I feel a little better about the castle nut and pin arrangement in a major control like the elevator. I lost my best friend and building mentor over a failed elevator control. It makes me a little nervous. The bottom picture is some hardware I found on the Aircraft Spruce website.  

Vance

2017-10-03 20.35.31.jpg

2017-10-03 20.38.10.png

Share this post


Link to post
Share on other sites

Posted

I did not have them on control surfaces, but on a throttle quadrant and over a 5 year period they held up great.  It is always nice to have castlenuts and cotter pins...sorry if I lead you in a bad direction, but I think you found a good compromise.

Is this all because of a modification someone made to that arm?  It seems that if it were standard the other guys would have this solved already.

 

Ron

Share this post


Link to post
Share on other sites

Posted

No need to be sorry Ron I had two other people think that it was acceptable including myself. The nice thing about Aviation Hardware as you can look up its specifications somewhere. Aircraft Spruce normally has a decent description of the item on their website.

Im not sure what the original builders was trying to accomplish. The tab is sturdy for sure but does not look pretty. I have a couple of other small projects over the Idaho winter planned and this will be another one. I will take this all apart and refab the end back to the original configuration.

Vance

1 person likes this

Share this post


Link to post
Share on other sites

Posted (edited)

I checked my Avid MK IV today, the with the tape against the bottom of the elevator, the center of the bolt was 2" down.   Meant to get a picture of my stop on the joystick, but forgot to do it.  Anyway, that is real important to have a good stop on the joystick that doesn't put pressure on the heim joint at the end of the elevator control tube.  JImChuk

PS  just doing a little searching for the info on an elevator stop, and I see you aren't the first person with the bolt hitting things.  

Edited by 1avidflyer

Share this post


Link to post
Share on other sites

Posted (edited)

I am a little confused on this - First posts I thought were showing rear of elevator tube and fuselage tubes - Then I think I was seeing the cockpit controls?  Maybe Avids are made different than Kitfoxes there?   Anyway, on my Foxy and other Kitfoxes, there is a short, curved round bar that is welded between the fuselage tubes that come to a V, and that serves as a forward (down) stop for the elevator flat bar that connects to the push-pull tube - for the rear (up) stop the flat bar hits the vertical post that the rudder connects to.  Jim Chuk has a stripped Kitfox 4 and might be able to get a photo, if it is the same as my earlier design - if not, I will try to get one this next weekend, but my controls are not hooked up, since I am changing from a fork on the end of push-pull to a rod end and don't have elevator horn made yet. - I am busy until then.  EDMO

Edited by EDMO

Share this post


Link to post
Share on other sites

Posted (edited)

I wonder why they modified that elevator horn in the first place? Repair for a broken horn or attempt to fix poor rigging with new geometry? That sure looks a whole lot tighter than normal. I don't have any really good close up pics from my Mk-IV build but, if you can zoom in, these might help show the normal clearances with correct hardware.

image.jpeg

 

image.jpeg

image.jpeg

image.jpeg

Edited by dholly

Share this post


Link to post
Share on other sites

Posted

Hey Vance,

please do remove your "washer" elevator stop. There has been loss of elevator control before when installing an inadequate elevator stop. In your case the washer puts the wrong pressure on the Heim joint threads, that thread is supposed to work only in tension/compression and NOT in a bending force (up/down).

My 2 cents...cheers

Share this post


Link to post
Share on other sites

Posted

I will remove the washer and come up with a different way of adding a stop. I appreciate the feedback on this.

Vance

 

Share this post


Link to post
Share on other sites

Posted

I remembered to get the pictures of my MK IV elevator stop today after I came back from an evening flight.  Not exactly what Avid recommended  (where is that info Doug?)  but it works fine and was easy to do.  Last picture is with the stick all the way forward, and the elevator control rod doesn't touch the cross tube. JImChuk

Photo1357.jpg

Photo1358.jpg

Photo1362.jpg

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now